Single-lens reflex camera with exposure meter

ABSTRACT

A camera is provided with a photoelectric exposure meter influenced by light passing through a detachable objective lens having a diaphragm presetting control. A first indicating means is influenced by a photoelectric device of the exposure meter and a second indicating means is movable by a first setting element provided on the lens adjustable by the diaphragm presetting control. A second setting element on the lens is positioned according to the maximum aperture of the lens and operates one of the first and second indicating means. Alignment of the first and second indicating means by adjustment of the diaphragm presetting control sets the value required for accurate exposure. A lens without diaphragm presetting control and without setting elements can be used when the first and second indicating means attain a predetermined relative position and alignment of the two indicating means by adjustment of the lens diaphragm indicates that the aperture is set to a value required for accurate exposure.

United States Patent Horst Strehle;

[72] Inventors Walter Hennig; Manfred Wiessner; Heinz Schulze, all ofDresden, Germany 211 Appl. No. 799,060 [221 Filed Feb. 13, 1969 [45]Patented Sept. 7, i971 (73] Assignee VEB Pentacon Dresden Karnera-undKinowerke Dresden, Germany [54] SINGLE-LENS REFLEX CAMERA WITH EXPOSUREMETER 5 Claims, 4 Drawing Figs.

[52] U.S. Cl 95/42, 95/10 C [51] lnt.Cl ..G03b 19/12 50 Field of Search95 42, 10 C, 11, 44

[561 References Cited UNITED STATES PATENTS 3,262,380 7/1966 WinklerPrimary Examiner-Samuel S. Matthews Assistant ExaminerRichard L. MosesAttorney-Young & Thoi'npson ABSTRACT: A camera is provided with aphotoelectric exposure meter influenced by light passing through adetachable objective lens having a diaphragm presetting control. A firstindicating means is influenced by a photoelectric device of the exposuremeter and a second indicating means is movable by a first settingelement provided on the lens adjustable by the diaphragm presettingcontrol. A second setting element on the lens is positioned according tothe maximum aperture of the lens and operates one of the first andsecond indicating means. Alignment of the first and second indicatingmeans by adjustment of the diaphragm presetting control sets the valuerequired for accurate exposure. A lens without diaphragm presettingcontrol and without setting elements can be used when the first andsecond indicating means attain a predetermined relative position andalignment of the two indicating means by adjustment of the lensdiaphragm indicates that the aperture is set to a value required foraccurate exposure.

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PATENTEDSEP mm 3.603.234

SHEET 2 0F 2 V Ava/7 A M M' SINGLE-LENS REFLEX CAMERA WITH EXPOSUREMETER BACKGROUND TO INVENTION The invention relates to a single-lensreflex camera with an exposure meter in which a photoelectric cell isinfluenced by light passing through an interchangeable lens, the settingmeans for the exposure meter being capable of being coupled, when aspecial lens is attached, both with a diaphragm setting device on thelens, for setting a preselected diaphragm aperture, and with a settingelement of the lens for presetting its maximum aperture.

Known measuring devices of this kind, such as described in E. Ger. Pat.No. 43 W2 and Brit. Pat No. 1,099,172, perform a measuring function whenthe lens diaphragm is fully open. In order to accommodate lenses havingdifferent maximum apertures, each lens has to be provided with a devicewhich presents the exposure meter according to the particular maximumapertures and in the case of preselector diaphragms, provides a controldependent on the preselector diaphragm setting. With these known devicesonly special lenses equipped with the device can be utilized. An objectof the invention is to provide a camera which overcomes thisdisadvantage and permits a standard lens to be utilized with the camera.

SUMMARY OF THE INVENTION According to the invention a photographiccamera having a housing is provided with an exposure meter arranged onthe housing'and including a photoelectric device for illumination bylight passing through a detachable objective lens mounted on thehousing, which objective lens includes a diaphragm presetting control,first indicating means arranged on the housing and influenced withregard to position by the photoelectric device in accordance withprevailing light conditions, a second indicating means movable withinthe housing by a first setting element provided on the objective lens,the position of which setting element being adjustable by movement ofthe diaphragm presetting control of the lens and a second settingelement provided on the lens operatively connectable with one of theindicating means selected from the group consisting of said first andsecond indicating means, the position of which second setting elementbeing arranged according to the maximum aperture of the attached lensand being effective to preset the exposure meter according to themaximum aperture of the lens by moving said selected indicating meanswhereby, alignment of the first indicating means and the secondindicating means by means of the diaphragm presetting control of thelens presets the aperture to a value required for accurate exposure andin the event of an objective lens having a diaphragm control withoutpresetting control and without setting elements being attached, thefirst and second indicating means attains a predetermined relativeposition which is capable of alteration by adjustment of the lensdiaphragm aperture until the first indicating means is aligned with thesecond indicating means thereby providing an indication that theaperture is set to a value required for accurate exposure.

Brief Description of Drawings The invention is explained by reference tocertain examples illustrated and described in the accompanying drawingin which:

FIGS. 1 and 2 show an exposure meter in conjunction with special lenseshaving a correction value lug separate from the diaphragm stop adjuster,and

FIGS. 3 and 4 show an exposure meter in conjunction with special lenseshaving a correction value lug connected with the diaphragm stopadjuster.

SPECIFIC DESCRIPTION In a partly illustrated camera housing 1 (cf. FIGS.1 and 2) the galvanometer is mounted so that it can rotate about itsshaft 3. The moving coil of the galvanometer 2 bears a first indicatingmeans in the form of a needle 4 and is connected in a know manner to aphotoelectric cell which is illuminated by rays passing through aninterchangeable lens 5a, b etc. The galvanometer 2 is subjected to theaction of an adjuster spring 6 which tends to rotate the galvanometer 3in a clockwise direction as viewed in the drawings.

A galvanometer 2 is provided with a stop arm 7, the adjustable stop 8,being situated opposite the latter, and with a regu' lating arm 9 whichcan be acted on by second setting elements in the form of maximumaperture adjusting abutments, I00, l0b...10 rigidly pull tab on theinterchangeable lenses. The length of the abutments 10a, l0b...l0ncorresponds to the particular maximum aperture of the lens. From thescale 11, which serves solely for clarification, a reading can be takenof the diaphragm value of the maximum opening of the attached lens,which value had been provided by the abutments 10a, 10b....l0n which setthe position of regulating arm 9 of the exposure meter. The position ofthe stop 8 corresponds to the maximum opening of the fastestinterchangeable lens, in the present example 1.4.

Opposite the needle 4 of the galvanometer 2 a second indicating means ora followup needle 12 is mounted adjustably and concentrically with thegalvanometer 2. An adjusting spring 13 tends to rotate the followupneedle 12 in a clockwise direction about its initial position as viewedin the drawing, thus causing the stop arm 14 to come to rest against theadjustable stop 15. The position of the stop 15 corresponds to themaximum opening of the fastest attachable lens, in the present case 1.4.A regulating arm 16 of the followup needle 12 is mounted opposite firstsetting elements in the form of diaphragm stop adjusters 17a, l7b...l7nwhich are mounted in an axially movable manner on the interchangeablelenses 5a, 5b...5n. A diaphragm scale 18 can be adjusted to any desiredvalue corresponding to the maximum value of an attached lens, by thediaphragm stop adjuster 17a, l7b...l7n on the lens side, by rotating thediaphragm rings 18a, I8b...l8n in relation to the diaphragm scales 19a,l9b...I9n on the lens side.

When the lens 5a is attached (cf. FIG. 1) the axially movable diaphragmstop adjuster 17a and the rigid correction value lug 10a make contactwith the regulating arm 16 of the followup needle 12 and the regulatingarm 9 of the galvanometer 2 respectively. The followup needle 12 and thegalvanometer 2 are thus rotated counterclockwise as viewed in thedrawing from their initial positions defined by the stops l5 and 8. Thegalvanometer 2 is caused to assume an unalterable position,predetermined by the length B4 of the correction value lug 10a, whilethe followup needle I2 is adjustable in accordance with the length A4 ofthe diaphragm stop adjuster 17a. The abutments 10a, l0b....10n adjustthe stop of the needle 4, in accordance with the maximum aperture of theparticular lens 5a, 5b...5n selected, so that despite a difference inthe maximum openings of the attachable lenses 5a, 5b...5n identicalmeasuring results are obtained for a given amount of light. With themaximum openings selected for the lens diaphragm the formula 0 8b,, 8=sb, const. applies where a, b a, and 4-b are the lengths of the lugs 17a,17b and 10a, 10b as shown in FIGS. 1 and 2. The correct diaphragm valuefor a given brightness is preselected when the followup needle has beenmoved so that it is situated opposite to the needle 4 of thegalvanometer 2.

When a lens is attached that has no diaphragm stop adjuster 17a, 17b,17!: or abutment 10a, 10b, I0n capable of being coupled with thefollowup needle 12 on the camera side and with the galvanometer 2 on thecamera housing then the followup needle 12 and the galvanometer 2, as aresult of the adjusting springs l3 and 6, are moved into their initialpositions defined by the stops l5 and 18. By partly closing the lensdiaphragm the photoelectric cell can be dimmed to the extent required toensure that the needle 4 will be opposite to the followup needle 12resting against the stop 15. In the event of coincidence between thefixed followup needle 12 and the needle 4 of the galvanometer 2 thediaphragm aperture suitable for prevailing light conditions has beenreached.

Another version is shown in FIGS. 3 and 4. In a partly illustratedcamera housing the galvanometer 21 is mounted so as to be rotatableabout its shaft 22 and can be adjusted in accordance with a scale 23with values for exposure times (or other exposure factors). The movingcoil of the galvanometer 21 bears a needle 24 and is connected in aknown manner to a photoelectric cell which is illuminated by rayspassing through the camera lens 25a, 25b...25n.

Opposite the needle 24 of the galvanometer 21 scanning device in theform of a followup needle 26 is mounted adjustably and concentricallywith the galvanometer 21. An adjusting spring 27 tends to cause a stoparm 28 to come to the rest against a adjustable stop 29, thus moving thefollowup needle 26 into its initial position. A regulating arm 30 of thefollowup needle 26 is mounted opposite a diaphragm stop adjuster 27a,27b...27n mounted on the interchangeable lenses 25a, 25b...25n in such away as to be axially movable, each of the diaphragm stop adjustershaving a first setting element in the form of a maximum apertureadjusting abutment 28a, 28b...28, respectively, corresponding to themaximum opening of the lens. The length d of the correction value lugs28a, 28b...28 are such that their end faces, interacting with theregulating arm 30 of the followup needle 26, are at the same distancefrom the bearing surface of the lens whenever the maximum opening of thelens diaphragms is set, i.e. the initial position of the followup needle26, defined by the stop 29, corresponds to the position assumed by thefollowup needle 26, in the case of the preselected maximum opening ofthe lens diaphragm. A sensing element 31, provided on the camera housingengages with the diaphragm stop adjusters 27a, 27b...27n, and is coupledwith a diaphragm indicator 32, which enables diaphragm valuespreselected on the lens to be additionally indicated.

When one the the lenses 25a, 25b...25n is attached the abutments 28a,28b...28n connected with the diaphragm stop adjusters 27a, 27b...27npress against the regulating arm 30 of the followup needle 26. In theevent of the preselected maximum opening the followup needle 26 remainsin the initial position defined by the stop 29. By moving the diaphragmstop adjuster 27a, or 27b from the position corresponding to the maximumdiaphragm aperture into one of the smaller diaphragm apertures thefollowup needle 26 is lifted off the stop 29, in opposition to theadjusting spring 27 and by means of the relevant abutments 28a or 28b.in this movement of the diaphragm stop adjusters 27a, 27b...27n thediaphragm remains fully open. The diaphragm aperture for the correctbrightness has been preselected if the followup needle 26 is situatedopposite to the needle 24 of the galvanometer 21.

When a lens is attached which has no diaphragm stop adjuster 27a,27b...27n capable of being coupled with a followup needle 26 then thefollowup needle 26 remains in the initial position defined by the stop29. By partly closing the lens diaphragm the photoelectric cell can bedimmed to the extent required to ensure that the needle 24 of thegalvanometer 21 is situated opposite to the followup needle 26. ln theevent of coincidence between the fixed followup needle 26 and the needle24 the diaphragm aperture suitable for prevailing light conditions hasbeen set.

We Claim:

1. In a single lens reflex camera having a housing, the provision of anexposure meter arranged on the housing and including a photoelectricdevice for illumination by light passing through a detachable objectivelens mounted on the housing, which objective lens includes a diaphragmpresetting control, first indicating means arranged on the housing andinfluenced with regard to position by the photoelectric device inaccordance with prevailing light conditions, a second indicating meansmovable within the housing by a first setting element provided on the obective lens, the positlon of WhlCh setting element being adjustable bymovement of the diaphragm presetting control of the lens and a secondsetting element provided on the lens operatively connectable with one ofthe indicating means selected from the group consisting of said firstand second indicating means, the position of which second settingelement being arranged according to the maximum aperture of the attachedlens and being effective to preset the exposure meter according to themaximum aperture of the lens by moving said selected indicating meanswhereby, alignment of the first indicating means and the secondindicating means by means of the diaphragm presetting control of thelens presets the aperture to a value required for accurate exposure andin the event of an objective lens having a diaphragm control withoutpresetting control and without setting elements being attached, thefirst and second indicating means attains a predetermined relativeposition which is capable of alteration by adjustment of the lensdiaphragm aperture until the first indicating means is aligned with thesecond indicating means thereby providing an indication that theaperture is set to a value required for accurate exposure.

2. A camera according to claim 1, wherein the first indicating meanscomprises a pivotably mounted galvanometer pivotable to preset thegalvanometer to compensate for different exposure factors.

3. A camera according to claim I, wherein the first indicating meanscomprises a pivotably mounted galvanometer urged in one pivotaldirection towards an adjustable stop by a second means and movable inthe other pivotal direction against the action of the spring means bythe second setting element of the objective lens.

4. A camera according to claim 3 wherein the housing is provided with anaperture scale and the body of the first indicating means is providedwith a pointer which pointer is effective to indicate on the scale themaximum aperture of an attached objective lens provided with a secondsetting element.

5. A camera according to claim 1 wherein there is provided a scale onthe housing and an arm mounted on the housing movable across the scaleby means of the first setting the lug of the objective lens to indicatethe factor to which the diaphragm presetting device has been set.

1. In a single lens reflex camera having a housing, the provision of anexposure meter arranged on the housing and including a photoelectricdevice for illumination by light passing through a detachable objectivelens mounted on the housing, which objective lens includes a diaphragmpresetting control, first indicating means arranged on the housing andinfluenced with regard to position by the photoelectric device inaccordance with prevailing light conditions, a second indicating meansmovable within the housing by a first setting element provided on theobjective lens, the position of which setting element being adjustableby movement of the diaphragm presetting control of the lens and a secondsetting element provided on the lens operatively connectable with one ofthe indicating means selected from the group consisting of said firstand second indicating means, the position of which second settingelement being arranged according to the maximum aperture of the attachedlens and being effective to preset the exposure meter according to themaximum aperture of the lens by moving said selected indicating meanswhereby, alignment of the first indicating means and the secondindicating means by means of the diaphragm presetting control of thelens presets the aperture to a value required for accurate exposure andin the event of an objective lens having a diaphragm control withoutpresetting control and without setting elements being attached, thefirst and second indicating means attains a predetermined relativeposition which is capable of alteration by adjustment of the lensdiaphragm aperture until the first indicating means is aligned with thesecond indicating means thereby providing an indication that theaperture is set to a value required for accurate exposure.
 2. A cameraaccording to claim 1, wherein the first indicating means comprises apivotably mounted galvanometer pivotable to preset the galvanometer tocompensate for different exposure factors.
 3. A camera according toclaim 1, wherein the first indicating means comprises a pivotablymounted galvanometer urged in one pivotal direction towards anadjustable stop by a second means and movable in the other pivotaldirection against the action of the spring means by the Second settingelement of the objective lens.
 4. A camera according to claim 3 whereinthe housing is provided with an aperture scale and the body of the firstindicating means is provided with a pointer which pointer is effectiveto indicate on the scale the maximum aperture of an attached objectivelens provided with a second setting element.
 5. A camera according toclaim 1 wherein there is provided a scale on the housing and an armmounted on the housing movable across the scale by means of the firstsetting the lug of the objective lens to indicate the factor to whichthe diaphragm presetting device has been set.